Combined lightning-arrester and cut-out



(No Model.)

J. A. MQMANMAN. COMBINED LIGHTNING ARRESTER AND GUT0UT. No. 440,361.

Patented Nov. 11, 1890.

W LWveo o m UNITED STATES PATENT OFFICE.-

.IOIIN A. MCMANMAN, OF MILlVAUKEE, \VISCONSIN.

COMBINED LIGHTNING-ARRESTER AND CUT-OUT.

SPECIFICATION forming part of Letters Patent No. 440,361, dated November 11, 1890.

Application filed February 7,1890- Serial No. 339,567. (No model.)

To all whom it may concern:

Be it known that I, JOHN A. MQMANMAN, of Milwaukee, in the county of Milwaukee, and in the State of lVisconsin, have invented certain new and useful Improvements in Lightning-Arresters and Strong-Current Protectors for Electric Systems; and I do hereby declare that the following is a full, clear, and exact description thereof.

My invention relates to lightning-arresters and strong-current protectors for electric systems such as telegraphs and telephones, fire and police alarms, and the like; and it consists in certain peculiarities of construction, as will be fully set forth hereinafter, and subsequently claimed.

In the drawings, Figure l is a transverse section of a lightning or strong-current'arrester constructed in accordance with my invention, the section being taken on the line I l of Fig. at. Fig. 2 is an under side View, partially in section, of my safety-bridge. Fig. 3 is a transverse section of the same on the line 3 8 of Fig. 2. Fig. 4 is a plan view of a series of my improved lightning or strong-currentv arresters.

The object of my invention is to produce a simple and durable attachment which shall instantly break the circuit when abnormallypowerful currents are induced therein by lightning or by accidental contact with the conductors of high-tension circuits, and thus automatically protect the instruments from injury and also avoid all danger to operation upon the instruments.

A further object of my invention is to produce a much more compact arrangement than has heretofore been practicable in this class of devices, thus materially economizin g space.

These objectsI accomplish by virtue of the construction which I will now proceed to de scribe.

,A represents the base-board, of wood or other insulating material, on which my devices are arranged in sections of any suitable number, (three being shown, for example, in Fig. 4,) fifty or one hundred being placed closely together to economize space and for convenience.

B represents the ground-bar, formed of brass or other suitable metallic substance, which is secured to the base-board A in any suitable manner, as by screws (not shown) passing through the top of the bar into the base-board, and the said ground-bar may be solid, if preferred, though a sheet of brass bent into continuous inverted-U forms, as shown, is equally elfective and cheaper. This bar extends continuously along the base-board, and is connected by a wire 2 (see Fig. 4:) with the ground, and at intervals on one side of this ground-bar are points a, projecting from it laterally, and preferably consisting of triangular pieces stamped out of the metal of one side and bent outward, as shown, for a purpose hereinafter explained.

O O are brass or other metallic springs of a general L shape, as shown, the lowerouter ends being turned up, as shown at 1), free from the base-board, and the inner upper ends being bent in to form catches, as shown at 0. These springs are secured to the base-board A, as by screws (1 and pins 6, there being preferably two securing devices to each spring to prevent any accidental lateral displacement of the same. Each lower outer end I? of each spring is preferably provided with a hole for convenience in soldering the ends of the wires D and F. to the spring, the wire D being the outside or line wire, and the wire E being the inside or officc wire, and the points a being formed, of course, on that side of the groundbar 13 next to the outer row of springs O, or those between the said ground-bar and the line-wire D.

F is what I term my safety-bridge, which is of wood, porcelain, hard rubber, glass, or other suitable insulating material, cut out at each end thereof on the under side, as shown at f f, to receive the catches c c of the springs C 0. Each of these bridges is also cut out transversely on the under side at a point between the ends, as shown at i, so as to rest above and preferably close to the top of the ground-bar B, which latter preferably projects up above the plane of the bottom of the said part F, as shown. The two cut-out ends ff are connected by a longitudinal under side groove 7L, and these cut-out ends ff and the groove h are provided with a partial filling G g G of fusible metal of any suitable nature, such as a composition of lead and zinc.

The operation of my device is as follows: In ordinary use (as in telephone or telegraph offices) each fusible metal filling G g G connects each two springs C O, which are opposite each other, and hence the ordinary elec tric current will pass uninterruptedly from the line-wire D to oifice-wire E; but when a current of more than ordinary strength strikes the line-wire D (as from a discharge of lightning or the possible crossing with said wire of an electric-railway or an electric-light wire) the metal filling .G g G would instantly melt, thereby breaking the line-circuit and stopping said current from reaching the officewire E. If this current were strong enough to ordinarily form an are between the springs C and C, it would be intercepted by the ground-bar B and form an are between each spring 0 and ground-bar B through the corresponding point a, While a current of lower voltage would merely burn out the fusible metal filling and leave the circuit open. Thus the current is rendered entirely harmless (so far as the ofiice-wire E is'concerned) in either instance.

The object of the insulating material of the safety-bridge F is to confine the effects of the electric spark from the unusual current to the space between the spring 0 named and the ground-bar and prevent the diffusion of heat and consequent fusing of the metal fillings of the adjacent bridges. 7

By the use of a continuously-raised groundbar between the line-wire and ofiice-wire I am enabled to bring these wires very closely together, and yet effectually prevent the formation of an are between them under the circumstances already stated.

The object of having the bridge F hold the free ends of the springs C O apart against the pressure or tension of said springs is to insure a better contact between the said ends of the springs and the interposed filling G g G of fusible metal, and the reason of confining the connecting portion g of said filling between the walls of the said under side groove h in said bridge is to prevent the radiation of the heat generated by a comparatively weak current, (which is yet much stronger than the ordinary current,) so that it will melt the fusible metal at a less temperature than if exposed to the influence of the atmosphere.

Heretofore in devices for the purpose of preventing the formation of an are between the adjacent ends of the line and office wires it has been found impossible to bring said adjacent ends nearer together than a space of four inches, which is a serious objection where hundreds or even thousands of these devices have to be employed in a comparatively limited space, as is common in tele- .phone offices, and I overcome this difficulty by the use of an intermediate continuous raised ground-bar, which enables me to bring said adjacent ends of the said line and office wires closely together, even a distance of half an inch apart having been found entirely practical.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is I 1. In a lightning-arrester and strong-current protector for electric systems, a continuously-raised elongated hollow ground-bar of inverted-U form in cross-section interposed between the line and office wires, with its longitudinal axis extending transversely of the terminals of said wires, the terminals of said wires being adjacent to opposite sidesof said bars, substantially as set forth.

2. In a lightning-arrester and strong-current protector for electric systems, a continuously-raised ground-bar, in combination with metallic springs connected closely adjacent to opposite sides of said bar and having the line and office wires attached to their outer ends, respectively, an insulating-bridge interposed between the free ends of the springs and sustained above the ground-bar by the pressure of said springs, and a fusible conduct-or carried by said bridge and normally establishing electrical communication between the springs, substantially as described.

3. In a lightning-arrester and strong-current protector for electric systems, a continuously-raised elongated hollow ground-bar of i inverted-U form in cross-section, in combination with two metallic springs located closely adjacent to opposite sides of the ground-bar and having the line and ofiice wires connected to their outer ends, respectively, and an insulating-bridge carrying on its under side a fusible conductor and supported above the ground-bar and separate therefrom by the upper inner ends of said springs, said ends of the springs being in contact with the fusible conductor, substantially as set forth.

4. In a lightning-arrester and strong-current protector for electric systems, the combi nation, with a raised gronml-bar, of metallic springs upon each side thereof connected to the line and office wires, respectively, and having catches at their free ends, a safetybridge of insulating material cut out on the under side at each end for the reception of said spring-catches and provided with a longitudinal groove on the under side connecting said cut-out ends, and a fusible metallic filling in said cut-out ends and groove, substantially as set forth.

5. In a lightning-arrester and strong-current protector, the combination of base-piece having a raised ground-bar with laterallyprojecting points on one side attached thereto, of metallic springs upon each side of said ground-bar, also mounted upon the base and pressing toward each other, connected to the line and office wires, respectively, and .a fusible metallic connection sustained between said springs by their spring-pressure, substantially as set forth.

In testimony that I claim the foregoing I have hereunto set my hand, at Milwaukee, in the county of Milwaukee and State of Wisconsin, in the presence of two witnesses.

JOHN A. MOMANMAN.

IIO 

